Sound is one of many forms of energy with which you must be familiar. Sound is a property of vibrating objects. These objects may be solids, liquids or gases.
Production of Sound
Sound can be produced by different types of objects. Some of the sound are appealing to the ear while others are not. However, you would have observed that there is something common to all sounding objects.
Transmission of Sound
Sound is propagated by means of longitudinal waves though an elastic medium. Typically, such a medium would be air, although sound may be transmitted through liquids and solids. The medium, air for example will at any instant have zones of COMPRESSION, where the air is more dense, and regions of RAREFACTION, where the air is less dense. Apart from transmission through the air, sound is also transmitted through metals and pipes. The sound may however be converted to electrical signals if it has to travel very long distances as the case of land telephones.
Reflection of Sound
Sound waves can be reflected in the same way as light waves. Sound waves are reflected by hard surfaces such as walls, rock and large concrete structures.
When you stood afar from a tall hill, a big building or a cave and you called a friend, after a short while you hear the call again. The phenomenon occurs as a result of the reflection of sound you made. The reflection of sound by a hard object, such as rock is called echo.
The ear is an organ of hearing and also helps in maintaining balance. Each person has two ears. The ear has three major parts namely: the outer part, the middle part and the inner part.
With our ears, sounds are heard and the direction from where the sounds are coming from is also known. Sound from the environment reaches the outer ear as vibration in the air. These vibrations are carried through the external auditory meatus to the eardrum which is the opening of the outer ear. The eardrum vibrates and passes the vibrations to the ear bones called the ossicles, which are in the middle ear. The ossicles also vibrate and transmit these vibrations to the oval window. The vibration of the oval window stimulates the sensory cells of the walls of the cochlea where the nerve endings are found and the nerve endings now pick the vibration (message) to the brain for interpretation and are sent back for response through the same nerves. The nerves ending responsible for this are called auditory nerves. Once the interpretation is made, we hear the sound and also detect the direction of the sound.
Enumerate on the following;
- Transmission of sound
- Reflection of sound